You can approximate where the drug is absorbed by the mode of administration. Commonly used modes of administration include oral, intramuscular, intravenous, topical and anal. 1. Oral administration: If the drug enters the body by oral administration, most of its absorption sites are located in the stomach and small intestine, and the drug enters the systemic blood circulation after being absorbed by the stomach and small intestine. 2. Intramuscular injection: intramuscular injection, referred to as intramuscular injection. The drug enters the human body through intramuscular injection, the drug spreads in the muscle, is absorbed by intramuscular blood vessels and enters the systemic blood circulation. 3. Intravenous drip: Intravenous drip, referred to as intravenous drip, the drug directly into the blood circulation. 4. Topical application: Topical application of drugs means that the drugs are directly applied to the surface of the skin, and the drugs are absorbed through the skin. 5. Nana-anal: It means that the drug is put into the intestines from the anus, absorbed by the intestinal mucosa and then enter into the blood circulation, and the absorption site of the drug is usually the intestinal mucosa. Please use the drug under the guidance of a doctor, do not take the drug on your own, so as not to delay the condition.